Liquid Level Sensing with Hall Sensors

Abstract

There are several approaches for liquid level sensing including capacitive, ultrasonic, magnetic, and mechanical solutions. Modern linear 3D Hall sensors allow us to measure the level of a liquid using a single sensor. This document covers a single-sensor implementation of liquid level sensing using a float arm and 3D linear hall sensor. The document discusses the design principles behind a Hall-based liquid level demo using the TMAG5273 linear 3D Hall-effect sensor, a float, and a magnet.

Trademarks

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1 Introduction

Determining the level of liquid inside a container is a common challenge across many industries and applications.

Around the house, liquid level sensing is used in mopping robots to let the user know when the robot has run out of cleaning solution.
Single cup coffee makers will detect when they are low on water and notify the user to add more water to brew a cup of a certain size.
Vehicles use liquid level sensing to detect when more windshield wiper fluid needs to be added to the reservoir. Every car has a fuel gauge displaying how full or empty the gas tank is.
Airplanes similarly measure the amount of fuel left.
Level sensors can shut down a unit if the liquid runs out, such as a humidifier turning off when the water tank is empty or an AC unit disabling itself if the drip pan isn't draining.

There are many applications for liquid level sensing around us every day, and there are many different measuring implementations.